The physical and mechanical properties of foams make them useful for a wide variety of applications. Flexible foams have been used in fabricating diapers, mop heads, sponges, and the like. More rigid and higher density foams have been used for bedding, for example mattresses also been used as replacement for wood. In each of the fields of use the foams have been susceptible to biological attack and mechanical abuse.
It is well known that diapers, mop heads, mattresses, and the like, are utilized under conditions wherein the foams are subjected to microorganisms which cause odors, degrade the foam or result in an unsanitary condition. Rigid foams are commonly used outdoors or at locations which promote growth of fungus and/or mold that degrade the foams or render them unattractive.
There are many antimicrobial preparations for suppressing mold, mildew and odor-causing bacteria. Such preparations include solid biocide concentrates as described in U.S. Pat. No. 4,086,297. The commercial preparation of Morton Thiokol, Inc. sold under the trademark VINYZENE is an additive to plastics which comprises 10, 10.sup.1 -oxybisphenozas that is active against a broad spectrum of fungi and bacteria. The product is in the form of a 2 weight percent solution in mineral spirits or methyl ethyl ketone and as a 5 weight percent blend in a thermoplastic resin. These products are used as biocides in the field of wood preservatives, swimming pools, food preservatives, sanitizers and disinfectants, industrial water treatment and plastics.
Biocides which are commercially available include active halogens, for example chlorine, chlorinated isocyanurates, halophors and the like, phenolics, quaternary ammonium salts including alkylbenzyl dimethylammonium chloride, where the alkyl group contains 12-18 carbon atoms and dimethyldialkylammonium chloride, where the alkyl group contains 8-10 carbon atoms.
These biocides however are leachable and can be lost in an aqueous environment.
There is a further need to provide some foams with reinforcement. It is common to provide high-density polyurethane foams with fiber reinforcement, such as fiberglass, wollastonite, etc. These reinforcing fibers are added together with fillers which include biocides, deodorizing agents and the like. The problem encountered in such cases is that the addition of fillers alters the physical characteristics of the foam.
U.S. Pat. No. 4,680,214 to Frisch et al, which is herein incorporated by reference, discloses a rigid polyurethane foam having suspended therein fillers and reinforcing fibers. The fibers comprise fiber glass or yarn strands which are near the surface.
U.S. Pat. No. 3,865,619 to Pennewiss et al discloses the preparation of anti-fogging hydrophilic resin coatings of an ethylenically unsaturated monomer, an acrylic acid or methacrylic acid and a quaternary ammonium salt. The quaternary ammonium salt is not biocidal.
U.S. Pat. No. 3,437,718 and 3,970,626, which are herewith incorporated by reference disclose suitable methods for preparing the precursor ionomers which may be used in the present invention.
U.S. Pat. No. 4,661,634 to Vaughn et al which is herein incorporated by reference, discloses the use of particles and fibers for removing impurities from quaternary ammonium salts.
The particles and fibers of Vaughn et al comprise an alpha olefin copolymerized with an olefinically unsaturated carboxylic acid which forms a "quat acrylate copolymer" when combined with quaternary ammonium salts.
Application Ser. No. 157,202 filed Feb. 17, 1988 of Patton et al entitled, "Polymer Salt Complex for Fiber or Fabric Treatment", which is herein incorporated by reference, discloses fabrics coated with copolymers of alpha olefins and beta-ethylenically unsaturated carboxylic acids that are modified with quaternary ammonium salts.
U.S. Pat. No. 4,837,079 to Quantrille et al discloses an antimicrobially active non-wooly web of cellulosic fibers bonded with a polymeric binder and having polyhexamethylene liquanide hydrochloride substantive to the fibers and bind as the antimicrobial agent.
U.S. Pat. No. 3,872,128 to Byck discloses an antimicrobial composition of carboxyl-containing alpha-olefin polymers which have been partially neutralized with quinoline or pyridine derivatives. However, hydrogels are not disclosed. The patent uses a melt process, a diffusion process and a dispersion process for preparing the antimicrobial compositions. In the melt process the reactants are refluxed with the removal of water. In the diffusion and dispersion processes the copolymer is stirred with a sodium hydroxide solution, treated with the antimicrobial agent and then treated with an acid. The acid prevents the formation of a hydrogel.
The article of Ackart et al entitled "Antimicrobial Polymers", J. Bromed. Mater. Res., Vol. 9, pp 55-68 (1975) discloses carboxy-containing alpha olefin copolymers having antimicrobial activity which are prepared to processes similar to those utilized in the aforementioned U.S. Pat. No. 3,872,128. The study eliminated the antimicrobial ionomers from consideration in applications such as surface treatments for hospital rooms, protective beds, pillow coverings, etc. The major area of use was in products intended to protect the article itself from microbial attack.
It should be understood that there is a distinction between the hydrogels of the invention which retain water and have the cationic biocide ionically bonded to the copolymer, and a copolymer which is merely swollen and then treated with a cationic biocidal agent without forming a hydrogel. In the hydrogel formation with the biocidal agent there are many carboxylic acid sites available for bonding.
The hydrogel is formed when the solution of cationic biocidal agent contacts the copolymer which is swollen with the base and water remains. Contacting the swollen copolymer or hydrogel with an acidic solution or refluxing off the water during ionic bonding prevents the hydrogel from forming.